In case of a short-circuit, the load current of a power semiconductor switching device increases to a saturation current Isat(Vge) and strongly heats the semiconductor switching device. Typically, a desaturation circuit detects a short circuit condition by comparing a voltage drop across the semiconductor device with a threshold voltage. If the voltage drop exceeds the threshold voltage, the desaturation circuit shuts off the gate signal of the semiconductor switching device in order to avoid its thermal destruction.
It is desirable to improve the reliability of power semiconductor switching devices at short circuits.